Wettability Of Polymers Research Articles

Engineering a superamphiphilic surface for enhanced interfacial bonding in metal-polymer hybrid structure

Insufficient wetting of polymer due to its poor compatibility with metals leads to non-intimate interfacial mutual contact during the thermal-direct bonding process, thus hindering the establishment of effective mechanical interlocking and substantial chemical bonding at the interface, resulting in deficient performance of metal-polymer hybrid structures. To achieve high-quality bonding between non-polar ultra-high molecular weight polyethylene (UHMWPE) and Ti6Al4V titanium alloy (TC4) for the application of artificial joint prostheses, this study innovatively engineered a superamphiphilic (simultaneously superhydrophilic and superlipophilic) TC4 surface, which was achieved through a morphology-chemistry dual regulation strategy. This pretreatment strategy aimed at improving the interfacial compatibility between in-situ oxidized UHMWPE and TC4 and ensuring intimate contact between these two materials during thermal-direct bonding, thus facilitating chemical reactions and mechanical interlocking at the interface. Defect-free and ultra-high-performance TC4-UHMWPE hybrid joints were successfully obtained via friction spot joining (FSpJ) with the lap shear strength reaching 18.05 MPa (higher than all those similar hybrid joints reported in existing literature) and the fracture was confined to the UHMWPE matrix, effectively avoiding interfacial failure. The formation of chemical bonds in the form of COTi at TC4/UHMWPE interface was solidly confirmed based on X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) analyses. This research presents a compelling strategy for improving interfacial compatibility between polymer and metal for thermal-direct bonding, to overcome the general difficulties in achieving effective interfacial bonding between these two categories of materials with significantly different physiochemical properties.

N‐heterocyclic carbene copper complexes catalyze the C1 polymerization of substituted diazomethanes

AbstractThe C1 polymerization of substituted diazomethanes, including diazoethane and 2,2,2‐trifluoromethyl diazomethane, are reported. N‐heterocyclic carbene copper complexes were employed as catalysts for the polymerization reactions and afforded the corresponding persubstituted polymers containing methyl or trifluoromethyl units along the backbones of the polymer products. The polymers were characterized using size exclusion chromatography, a variety of spectroscopic and thermal techniques, and contact angle measurements. Polymers prepared using the C1 polymerization methodology described herein are more hydrophobic than related polymers that were obtained using a standard C2 polymerization method and the fluorinated polymers were determined to be more hydrophobic than their hydrogenated analogues. The relationship between fluorine content and wettability of persubstituted polymers was quantified.

Modification of the Surface Crystallinity of Polyphenylene Sulfide and Polyphthalamide Treated by a Pulsed-Arc Atmospheric Pressure Plasma Jet.

Atmospheric plasma jets generated from air or nitrogen using commercial sources with relatively high energy densities are commonly used for industrial applications related to surface treatments, especially to increase the wettability of polymers or to deposit thin films. The heat fluxes to which the substrates are subjected are typically in the order of 100-300 W/cm2, depending on the treatment conditions. The temperature rise in the treated polymer substrates can have critical consequences, such as a change in the surface crystallinity or even the surface degradation of the materials. In this work, we report the phase transitions of two semicrystalline industrial-grade polymer resins reinforced with glass fibers, namely polyphenylene sulfide (PPS) and polyphthalamide (PPA), subjected to plasma treatments, as well as the modeling of the associated heat transfer phenomena using COMSOL Multiphysics. Depending on the treatment time, the surface of PPS becomes more amorphous, while PPA becomes more crystalline. These results show that the thermal history of the materials must be considered when implementing surface engineering by this type of plasma discharge.

Plasma Treatment of Nanocellulose to Improve the Surface Properties.

Nanocellulose is among the most promising materials for enhancing the mechanical properties of polymer composites. Broad application is, however, limited by inadequate surface properties. A standard technique for tailoring the surface composition and wettability of polymers is a brief treatment with non-equilibrium gaseous plasma, but it often fails when treating materials with a large surface-to-mass ratio, such as cellulose nanofibers. In this paper, the theoretical limitations are explained, the approaches reported by different groups are reviewed, and the results are interpreted. The treatment of dry nanocellulose is limited by the ability of uniform treatment, whereas the plasma treatment of nanocellulose dispersed in liquids is a slow process. The methods for enhancing the treatment efficiency for both dry and water-dispersed nanocellulose are explained.

The Role of Surface Energy and Wettability in Polymer-Based Drug Delivery Systems: Enhancing Bioadhesion and Drug Release Efficiency

Polymer-based drug delivery systems are pivotal in advancing the precision and efficacy of modern therapeutics. Among the key factors influencing these systems, surface energy and wettability are crucial in determining their interaction with biological tissues and drug release behavior. Surface energy, which governs the adhesive properties of the polymers, plays a significant role in bioadhesion—a critical aspect for drug delivery routes that require prolonged contact with biological surfaces, such as mucosal membranes. Wettability, the extent to which a polymer surface can be wetted by biological fluids, influences both drug loading efficiency and release kinetics. Hydrophilic polymers, characterized by high wettability, typically facilitate rapid drug release, whereas hydrophobic polymers, with low wettability, offer controlled, prolonged release profiles. Additionally, the balance between hydrophilicity and hydrophobicity is essential for optimizing drug-polymer interactions, particularly in systems designed for sustained or targeted drug delivery. Advances in surface modification techniques have enabled precise control over these parameters, allowing for the customization of polymers to meet specific therapeutic requirements. This review discusses the interplay between surface energy, wettability, and drug delivery performance, highlighting how these properties have been manipulated to enhance bioadhesion, drug retention, and release profiles. The review also addresses the challenges in designing polymer wettability, such as maintaining stability, scalability, and regulatory compliance. Finally, it explores emerging trends, including stimuli-responsive polymers and nanotechnology integration, which hold promise for the next generation of drug delivery systems that are more efficient, targeted, and patient-specific, than current systems.

Cold Atmospheric Pressure Plasma Solutions for Sustainable Food Packaging.

Increasing the number of resistant bacteria resistant to treatment is one of the leading causes of death worldwide. These bacteria are created in wounds and injuries and can be transferred through hospital equipment. Various attempts have been made to treat these bacteria in recent years, such as using different drugs and new sterilization methods. However, some bacteria resist drugs, and other traditional methods cannot destroy them. In the meantime, various studies have shown that cold atmospheric plasma can kill these bacteria through different mechanisms, making cold plasma a promising tool to deactivate bacteria. This new technology can be effectively used in the food industry because it has the potential to inactivate microorganisms such as spores and microbial toxins and increase the wettability and printability of polymers to pack fresh and dried food. It can also increase the shelf life of food without leaving any residue or chemical effluent. This paper investigates cold plasma's potential, advantages, and disadvantages in the food industry and sterilization.

Materials Characterization of Stereolithography 3D Printed Polymer to Develop a Self-Driven Microfluidic Device for Bioanalytical Applications.

Stereolithography (SLA) 3D printing is a rapid prototyping technique and reproducible manufacturing platform, which makes it a useful tool to develop advanced microfluidic devices for bioanalytical applications. However, limited information exists regarding the physical, chemical, and biological properties of the photocured polymers printed with SLA. This study demonstrates the characterization of a commercially available SLA 3D printed polymer to evaluate the potential presence of any time-dependent changes in material properties that may affect its ability to produce functional, capillary-action microfluidic devices. The printed polymer was analyzed with Fourier transform infrared-attenuated total reflectance, contact angle measurements, tensile test, impact test, scanning electron microscopy, and fluid flow analysis. Polymer biocompatibility was assessed with propidium iodide flow cytometry and an MTT assay for cell viability. The material characterization and biocompatibility results were then implemented to design and fabricate a self-driven capillary action microfluidic device for future use as a bioanalytical assay. This study demonstrates temporally stable mechanical properties and biocompatibility of the SLA polymer. However, surface characterization through contact angle measurements shows the polymer's wettability changes over time which indicates there is a limited postprinting period when the polymer can be used for capillary-based fluid flow. Overall, this study demonstrates the feasibility of implementing SLA as a high-throughput manufacturing method for capillary action microfluidic devices.

Kinetics of Surface Wettability of Aromatic Polymers (PET, PS, PEEK, and PPS) upon Treatment with Neutral Oxygen Atoms from Non-Equilibrium Oxygen Plasma.

The wettability of polymers is usually inadequate to ensure the appropriate spreading of polar liquids and thus enable the required adhesion of coatings. A standard ecologically benign method for increasing the polymer wettability is a brief treatment with a non-equilibrium plasma rich in reactive oxygen species and predominantly neutral oxygen atoms in the ground electronic state. The evolution of the surface wettability of selected aromatic polymers was investigated by water droplet contact angles deposited immediately after exposing polymer samples to fluxes of oxygen atoms between 3 × 1020 and 1 × 1023 m-2s-1. The treatment time varied between 0.01 and 1000 s. The wettability evolution versus the O-atom fluence for all aromatic polymers followed similar behavior regardless of the flux of O atoms or the type of polymer. In the range of fluences between approximately 5 × 1020 and 5 × 1023 m-2, the water contact angle decreased exponentially with increasing fluence and dropped to 1/e of the initial value after receiving the fluence close to 5 × 1022 m-2.

Two-step ion beam treatment for superhydrophilic fluorinated polymers

Plasma treatment is a widely used simple and ecofriendly method to improve the surface wettability of polymers. However, this is challenging for fluorinated polymers because of their robust CF bonds with low surface energies. Here, we demonstrated a simple approach, involving Ar-H2 and O2-H2 two-step ion beam treatments, to achieve superhydrophilic fluorinated polymer surfaces. The effects of surface roughness and chemical composition on the water contact angle (WCA) were studied using X-ray photoelectron spectroscopy, scanning electron microscopy, and atomic force microscopy. After the single H2 ion beam treatment on fluorinated ethylene propylene films, the WCA decreased from 110.2° to 35.2° due to defluorination and oxidation effects. However, the H2 ion beam treatment alone has a limited effect on the root-mean-square (RMS) roughness, which hinders achieving superhydrophilicity. In contrast, the WCA significantly decreased to 1.3° and 1.2°, respectively after the Ar-H2 and O2-H2 two-step ion beam treatments. Although the chemical composition after these treatments was similar to that after the single H2 ion beam treatment, the RMS roughness increased upon the Ar and O2 ion beam treatments because of the formation of nanostructures. Our results show that nanostructures with abundant polar oxygen bonds are required to obtain superhydrophilic surfaces in fluorinated polymers.

Water‐Soluble Ionic Liquid‐Containing Sulfur Polymers for Mercury Capture, Demulsification, and Antibacterial Activity

AbstractSulfur polymers, prepared by inverse vulcanization using elemental sulfur and vinylic monomers, are emerging functional materials of current research interest; however, sulfur polymers suffer from limited water solubility due to the hydrophobic nature of conventional comonomers and sulfur. Herein, the preparation of ionic liquid (IL)‐containing sulfur polymers are reported using the hydrophilic ionic liquid, 1‐allyl‐3‐vinylimidazolium chloride (AVImCl) as a comonomer. The introduction of IL significantly enhances the hydrophilicity of sulfur polymers, enabling them to dissolve in water. Benefiting from the thorough contact with aqueous mercury ions, the resultant sulfur polymer possesses high uptake capacity (436 mg g−1). After binding mercury, a coordination complex is formed and precipitated. The charged sulfur polymers gain a new application in demulsification. The polymer quickly breaks oil‐in‐water (O/W) emulsions through anion exchange between Cl− of the polymer and dodecylbenzenesulfonate (DBS−) of the surfactant. In addition, the polymer has a growth inhibitory effect against Staphylococcus aureus. The integration of IL and elemental sulfur provides a novel approach to modifying the wettability of sulfur polymers. Also, this novel water‐soluble IL‐containing sulfur polymer, with mercury capture, demulsification, and antibacterial activity, can be considered as a multifunctional material in practical water purification.

Polymer-Doped SnO2 as an Electron Transport Layer for Highly Efficient and Stable Perovskite Solar Cells.

To produce highly efficient and repeatable perovskite solar cells (PSCs), comprehending interfacial loss and developing approaches to ameliorate interfacial features is essential. Nonradiative recombination at the SnO2-perovskite interface in SnO2-based perovskite solar cells (PSCs) leads to significant potential loss and variability in device performance. To improve the quality of the SnO2 electron transport layer, a novel polymer-doped SnO2 matrix, specifically using polyacrylic acid, was developed. This matrix is formed by spin-coating a SnO2 colloidal solution that includes polymers. The polymer aids in dispersing nanoparticles within the substrate and is evenly distributed in the SnO2 solution. As a result of the polymer addition, the density and wetting properties of the SnO2 layer substantially improved. Subsequently, perovskite-based photovoltaic devices comprising SnO2 and Spiro-OMeTAD layers and using (FAPbI3)0.97(MAPbBr3)0.03 perovskite are constructed. These optimized devices exhibited an increased efficiency of 17.2% when compared to the 15.7% power conversion efficiency of the control device. The incorporation of polymers in the electron transport layer potentially enables even better performance in planar perovskite solar cells.

Degree of Wettability and Aging of PVC and PET Polymers Treated by Plasma Immersion or Deposition

The wettability, aging characteristics, and optical transmittance in the visible region following Plasma Immersion (PI) or Plasma Immersion Ion Implantation (PIII) treatment of polymers were studied. In addition, structural and chemical modifications of the polymers were examined. The polymers investigated were white Polyvinyl chloride (PVC) and Polyethylene terephthalate (PET). Initially, plasmas of nitrogen (N2) were employed, aiming to produce hydrophilic surfaces. In contrast, sulfur hexafluoride (SF6) plasma treatments produce high surface fluorination, which tends to increase hydrophobicity. Isopropyl alcohol (IPA) was mixed with SF6 or N2 to deposit a series of organic films. Aging effects over 30 days on the contact angle, q, were measured for the polymer surfaces. Conventional plasma immersion (PI) tended to decrease of θ for N2 plasma treatments, with or without IPA, and to increase θ values ​​for samples immersed in IPA/SF6 plasma. The highest value of θ was 140º for IPA/SF6 plasma treatments, while the smallest θ was 20º for N2 or IPA/N2 treatments. There was an ideal condition under which θ was stable upon aging. The results obtained suggest the developed treatment enables the preparation of polymers with distinct wettability properties depending of the nature of the plasma with overall reasonable aging stability. Moreover, the opaque character of these materials makes them interesting for the production of bags, boxes, bottles, food packaging, among others.

Correlating Surface Chemistry to Surface Relaxivity via TD-NMR Studies of Polymer Particle Suspensions.

This study elucidates the impact of surface chemistry on solvent spin relaxation rates via time-domain nuclear magnetic resonance (TD-NMR). Suspensions of polymer particles of known surface chemistry were prepared in water and n-decane. Trends in solvent transverse relaxation rates demonstrated that surface polar functional groups induce stronger interactions with water with the opposite effect for n-decane. NMR surface relaxivities (ρ2) calculated for the solid-fluid pairs ranged from 0.4 to 8.0 μm s-1 and 0.3 to 5.4 μm s-1 for water and n-decane, respectively. The values of ρ2 for water displayed an inverse relationship to contact angle measurements on surfaces of similar composition, supporting the correlation of the TD-NMR output with polymer wettability. Surface composition, i.e., H/C ratios and heteroatom content, mainly contributed to the observed surface relaxivities compared to polymer % crystallinity and mean particle sizes via multiple linear regression. Ultimately, these findings emphasize the significance of surface chemistry in TD-NMR measurements and provide a quantitative foundation for future research involving TD-NMR investigations of wetted surface area and fluid-surface interactions. A comprehensive understanding of the factors influencing solvent relaxation in porous media can aid the optimization of industrial processes and the design of materials with enhanced performance.

Enhancing Structural and Thermal Properties of Poly(lactic acid) Using Graphene Oxide Filler and Anionic Surfactant Treatment.

Graphene has attracted extensive attention in various fields due to its intriguing properties. In this work, nanocomposite films based on poly(lactic acid) (PLA and PLLA) polymers filled with graphene oxide (GO) were developed. The impact of treating GO with the anionic surfactant dioctyl sulfosuccinate sodium salt (AOT) on the properties of the resulting nanocomposites was investigated. To determine the morphological, optical, and structural properties of the obtained materials, physicochemical analyses were performed, including scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier-transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD) analysis. Additionally, the thermal properties and wettability of neat polymers and nanocomposites were thoroughly investigated using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and contact angle analysis. It was observed that GO was well dispersed throughout the PLA and PLLA matrix, leading to stronger interface bonding. The results demonstrate that the untreated and treated GO improved the crystallinity and thermal stability properties of the PLA and PLLA. However, the AOT-treated GO has significantly higher performance compared to the untreated GO in terms of crystallinity, melting temperature (increased by ~15 °C), and wettability (the contact angle decreased by ~30°). These findings reveal the high performance of the developed novel composite, which could be applied in tissue engineering as a scaffold.

Induced Wettability Switch in Thin Films of Conductive Polymer Coatings Exhibiting Hydrophobic/Hydrophilic Interactions.

The hydrophobic/hydrophilic character of some conductive polymer (CP) coatings can be switched in the function of the working conditions of these adaptive materials. We studied the influence of electrical stimuli and intrinsic physical characteristics (nature of the polymerizable core, dopants, the droplet dimension and physical properties, surface roughness, etc.) on the CP wettability. A simulation strategy was developed for determining the contact angle (CA) of a liquid droplet on a CP layer with roughness. The method was tested for new reported CP composites, but with new dopants. The results indicate that the influences on the material wettability are correlated, and in practice, modification of more than one parameter converges to a wanted behavior of the material. E.g., the CP porous film of poly(3-hexylthiophene) (P3HT) + [6,6]-phenyl-C61-butyricacid-methyl-ester (PCBM) changes its wettability at voltages of up to 26 V, but if doping ions are inserted and the roughness geometry is modified, the voltage decreases twice. Our multi-parametrical study points out that the polymer wettability type is driven by the voltage, but this effect is tuned differently by each internal parameter. The thin films' effect and the dopants (in-situ and ex-situ) significantly decrease the actuation voltage. We also illustrated that the wettability type does not change for specific sets of parameters.

Cell-Sized Confinements Alter Molecular Diffusion in Concentrated Polymer Solutions Due to Length-Dependent Wetting of Polymers.

Living cells are characterized by the micrometric confinement of various macromolecules at high concentrations. Using droplets containing binary polymer blends as artificial cells, we previously showed that cell-sized confinement causes phase separation of the binary polymer solutions because of the length-dependent wetting of the polymers. Here, we demonstrate that the confinement-induced heterogeneity of polymers also emerges in single-component polymer solutions. The resulting structural heterogeneity also leads to a slower transport of small molecules at the center of cell-sized droplets than that in bulk solutions. Coarse-grained molecular simulations support this confinement-induced heterogeneous distribution by polymer length and demonstrate that the effective wetting of the shorter chains at the droplet surface originates from the length-dependent conformational entropy. Our results suggest that cell-sized confinement functions as a structural regulator for polydisperse polymer solutions that specifically manipulates the diffusion of molecules, particularly those with sizes close to the correlation length of the polymer chains.

Dynamics of Polymers Flowing through Porous Media: Interplay of Solvent Properties, Flow Rates, and Wetting

Polymer transport in porous media controls many important industrial and technological applications. Using molecular simulations with fully coupled hydrodynamic interactions, we have previously studied the dynamics of polymers flowing through purely repulsive model porous media. The most prominent observation is the emerging of slow dynamics for the collapsed polymers at low flow rate, where the polymer transport is controlled by a globule–stretch transition at pore throats. In this work, we extend our previous work by including the wetting effect, i.e., the polymer–porous media interactions, which are ubiquitous in all realistic conditions. At high flow rate, the hydrodynamic drag forces can overcome the wetting interactions, and the polymer dynamics is like those without wetting interactions. On the other hand, at low flow rate, including polymer wetting results in rich nonmonotonic polymer transport dynamics: Weak polymer wetting in fact facilitates the polymer transport through porous media by converting 3D compact polymer globules into quasi-2D morphologies that can pass through the narrow pore throats more easily. In contrast, strong polymer wetting reduces the polymer transport especially for shorter chains, where the hydrodynamic drags are unable to pull the small polymer globules away from the porous media surfaces. To the best of our knowledge, this is the first comprehensive study showing the dynamics of polymers flowing through porous media with effects from the combinations of flow rates, solvent properties, and wetting interactions. We believe the results put forward in this study are important in understanding the fundamental nonequilibrium polymer dynamics in constraints as well as with practical implications for using polymers in subsurface applications and (bio)macromolecular separation technologies.

Wear and triboelectric performance of polymers with non-polar lubricants

Triboelectric nanogenerators (TENGs) convert kinetic energy into electrical energy based on triboelectrification and electrostatic induction. There are many benefits to TENGs, such as inexpensiveness, processability, and high applicability. However, friction and wear, in solid–solid contact TENGs, affect their lifespans. In this study, we evaluated the tribological behavior and electrical output of polymers in TENG systems with non-polar lubricants reducing friction and wear. The lubricant-dependent tribological behavior of polymers was influenced by the viscosity of lubricants and the wetting and mechanical characteristics of polymers. Furthermore, the electrical outputs of lubricant-based TENG system were improved and powered the electronic device. The comprehensive analysis on tribological behavior of lubricant-based TENGs in this study contributes to promote the reliability of lubricant-based TENG system.

Surface Modification of Polymethylmethacrylate (PMMA) by Ultraviolet (UV) Irradiation and IPA Rinsing.

Polymethylmethacrylate (PMMA) is commonly applied to microfluidic devices due to its excellent biocompatibility, high optical transparency, and suitability for mass production. Recently, various surface treatment methods have been reported to improve the wettability of polymers, which is directly related to adhesion. In this research, the effect of a UV irradiation technique and an IPA rinsing technique as surface treatments for PMMA is investigated regarding the water contact angle of the PMMA surface. PMMA sheets that were 1.62 mm thick and commercially available were exposed to UV light with four different exposure times. Significant decreases in the water contact angle were observed after exposure to UV light, and the lowered contact angles due to the UV irradiation increased over time. According to the measurement, the water contact angle is a function of UV exposure dose as well as storage time after UV exposure. We examined the effect of a IPA rinsing process after UV irradiation and observed an increase in the water contact angle.

Ameliorating the Mechanical Parameters, Thermal Stability, and Wettability of Acrylic Polymer by Cement Filling for High-Efficiency Waterproofing.

Acrylic polymer/cement nanocomposites in dark and light colors have been developed for coating floors and swimming pools. This work aims to emphasize the effect of cement filling on the mechanical parameters, thermal stability, and wettability of acrylic polymer. The preparation was carried out using the casting method from acrylic polymer coating solution, which was added to cement nanoparticles (65 nm) with weight concentrations of (0, 1, 2, 4, and 8 wt%) to achieve high-quality specifications and good adhesion. Maximum impact strength and Hardness shore A were observed at cement ratios of 2 wt% and 4 wt%, respectively. Changing the filling ratio has a significant effect on the strain of the nanocomposites. The contact angle was increased as the concentration of additives and cement increased, indicating that the synthesized coating is not hydrophilic and does not allow water permeability through it. The results show that the acrylic polymer/cement with a cement ratio of 8 wt% is the best nanocomposite for high-efficiency waterproofing.